Why does the Front Toric lens require prism ballast?

The need for prism ballast in Front Toric lenses is primarily related to stabilization. Toric lenses are designed to correct astigmatism, and the way in which they sit on the eye is critical for effective vision correction.

When a toric lens is crafted, it is shaped differently in two meridians to account for the varying curvature of the cornea. If the lens were to rotate on the eye, it could lead to misalignment of the corrective optical zone and thus result in blurred or distorted vision. The prism ballast helps to maintain the lens's orientation by adding weight at the bottom of the lens. This design encourages the lens to settle in a stable position on the eye, ensuring that the meridian meant for astigmatic correction remains aligned with the correct axis on the cornea.

Other choices, while important in different contexts, do not explain the specific role of prism ballast. For instance, better vision quality can be a result of proper stabilization, but it does not address the mechanism of how prism ballast achieves that. Similarly, reducing glare and correcting color vision are not related to the stabilization function that prism ballast provides for toric lenses. Thus, prism ballast is fundamentally essential for ensuring that the lens remains in the correct position for